TUESDAY, April 29, 2014 (HealthDay News) -- Kidney stone treatments cause complications in about 14 percent of patients and can be costly, according to a large new study.

Researchers analyzed data from more than 93,000 privately insured patients in the United States who were treated for kidney stones.

One in seven of the patients experienced complications that required hospitalization or emergency care within 30 days of treatment the study found. The average cost of treating complications was $30,000 per patient.

The study looked at three methods of treatment, including shock-wave lithotripsy, ureteroscopy and percutaneous nephrolithotomy.

In shock-wave lithotripsy, a machine known as a lithotripter is used to crush the kidney stone, according to the U.S. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Ureteroscopy involves using a long, tube-like instrument to find or break up the stone. Percutaneous nephrolithotomy uses a wire-thin viewing instrument to locate and remove the stone.

All three procedures require anesthesia, according to the NIDDK.

In the new study, rates of complications were 12 percent for patients who had shock-wave lithotripsy and 15 percent for those who underwent ureteroscopy. The average cost of treating complications after nephrolithotomy was $47,000, compared with $32,000 for complications after shock-wave lithotripsy.

Patients treated at hospitals that performed large numbers of kidney stone procedures were much less likely to have complications, according to the study published April 28 in the journal Surgery.

"Our findings provide a good starting point to understand why these complications are happening and how they can be prevented, because the costs to patients who suffer complications and to the health care system are substantial," lead author Dr. Charles Scales Jr., an assistant professor of surgery at Duke University, said in a university news release.

Further research is needed to learn why the three kidney stone treatments had different complication rates and costs, the study authors noted.

"From the patient perspective, an unplanned emergency department visit or hospital admission after a low-risk ambulatory procedure is a significant event," Scales said. "Kidney stones are excruciatingly painful and primarily affect people who are of working age. These patients face not only the cost of treatment, but also the financial difficulties from time off work due to pain and treatment."